sounds like u left it ticking over at idle for abit? my old driver used to tap its tappity ass off. give it some right foot into the rev limit are sorted that for about 5 minutes. suppose the pumps get older they need more revs to get pressure and the tappets they just give up the ghost eventually i guess
You lose nothing by using high revs to try to 'pump up' the tappets. Its usual practice but don't destroy the rest of the engine by persuing this avenue if it does not work within a couple of minutes. Also wait till the engine is warmed through.
I don't think a semi will give the same results
when i fired up my project for the first (and only) time, after being stored for 2 years, the noise was terrible!given 15 minutes it was purring like a kitten.so there is hope